Cigarette smoking is of great public health importance and is the single most important preventable cause of morbidity, mortality and excess health care costs in the United States. After a steady decline for the last 50 years, the prevalence of tobacco use in the U.S. seems to have reached a plateau. Currently available treatments among adults are not efficacious for all tobacco users, and new pharmacological agents need to be investigated to achieve the Healthy People 2010 goal of less than a 12% adult tobacco use prevalence. Gabapentin, an anti-epileptic agent, is reported to have potential efficacy in decreasing symptoms of alcohol and cocaine withdrawal. The effect of gabapentin on two of the neurotransmitters, gamma- aminobutyric acid (GABA) and glutamate suggest a potential therapeutic mechanism for this agent in tobacco abstinence. We have recently completed a pilot trial testing the efficacy of gabapentin for tobacco abstinence in 50 smokers. The promising results from this study suggest that further testing of gabapentin for helping cigarette smokers achieve tobacco abstinence is warranted. Gabapentin is generally well tolerated and has a low potential for abuse. To date, no prospective randomized clinical trial evaluating the efficacy of gabapentin for the treatment of tobacco dependence has been published. We propose to evaluate the efficacy of gabapentin for increasing smoking abstinence and decreasing nicotine withdrawal symptoms in a randomized, blinded, placebo- controlled, three-arm, parallel-group, dose-ranging phase II clinical trial. Participants (N=120) will be randomly assigned to one of the three groups, and will receive a 12-week course of gabapentin 1800-mg per day, 2700-mg per day, or a matching placebo. This proposal, an R-21 grant application, is anticipated to provide additional evidence of efficacy, and information on the optimal dose of gabapentin to employ in the larger randomized controlled trial, if the results from this study seem promising. [unreadable] [unreadable] [unreadable]